Aqueous compositions such as polymer latexes and latex paints exhibit a tendency toward foaming because they contain surface active agents such as soaps, and synthetic detergents. In many instances, such compositions produce excessive foam and the user must use substances known as anti-foaming agents or defoamers. Some defoamers such as silicones tend to interfere with the function of these compositions in that they interfere with the basic function of a product such as a water-based paint after it has been deposited on a surface. Defoamers comprised of waxes dispersed in paraffin oil have been in aqueous systems such as latexes and latex paints. These types of defoamers suffer from a number of deficiencies such as poor defoaming or their defoaming effect is relatively short-lived, and a tendency to reduce the scrub resistance of paints in which they have been used.
The surprising discovery has been made that the products of the reaction of epichlorohydrin and compounds having the formula II
R3(EO)n(PO)mxe2x80x94OHxe2x80x83xe2x80x83(II)
wherein R3 is an alkyl, alkenyl or arenyl group having from 4 to 22 carbon atoms; a substituted alkyl or alkenyl group having from 4 to 22 carbon atoms wherein; n is a number from 0 to 50 and m is a number from 0 to 50; wherein the mole ratio of epichlorohydrin to (II) is from about 0.60/1 to about 2/1 are extremely efficient defoamers for aqueous systems such as latexes and latex paints. These reaction products are added to the aqueous systems in an amount sufficient to reduce or eliminate foam.
Another aspect of the invention pertains to a multi-component defoamer for aqueous systems such as latexes and latex paints. The multi-component defoamer according to the invention is a composition comprised of a hydrophobic solid, one or more reaction products according to the invention dispersed and an inert water-insoluble liquid carrier such as a paraffin oil. These defoamers exhibit enhanced defoaming properties and good persistence in paints into which they have been added.
Not Applicable.
The term defoamer as used herein includes the reduction and/or prevention of foam or foaming in aqueous systems. An aqueous system is any aqueous medium such as an aqueous solution, dispersion or emulsion. The reaction products as described herein below can be used as defoamers for aqueous systems in several ways. One way is by adding the reaction products themselves to an aqueous system such as a latex or a latex paint in an amount effective to eliminate or decrease the foam generated as a result of some type of mechanical action such as mixing, pouring, applying to a surface such as by a brush or a roller, and/or shaking. The amount required to eliminate and/or decrease foam is defined as a defoaming effective amount and will vary from one instance to another depending upon the nature of the aqueous system and the defoaming effect desired. A defoaming effective amount will be readily determinable by one of ordinary skill in the art will typically vary from about 0.001% to about 10.0%, preferably from about 0.1% to about 3.0% by weight.
Another way is by adding to an aqueous system a mixture comprised of one or more reaction products according to the invention and a carrier oil base. The carrier oil base useful in the process according to the invention is any water-insoluble liquid that will dissolve and/or disperse one or more reaction products according to the invention. Such carrier bases include but are not limited to paraffinic and naphthenic oils, tall oil fatty acids and alkoxylated tall oil fatty acids, fatty alcohols and alkoxylated fatty alcohols, liquid polypropylene oxide, liquid polyethylene oxide, liquid poly(ethylene oxide-propylene oxide) or any combination thereof. The relative amount of reaction products according to the invention in the mixture with the carrier oil base will typically range from about 1% to about 50% by weight and will preferably be from about 1% to about 20% by weight. A defoaming effective amount of such a mixture will be readily determinable by one of ordinary skill in the art and will typically vary from about 0.01% by weight to about 10%, preferably from about 0.1 to about 2.0% by weight.
Yet another way of using the reaction products according to the invention in defoaming applications is as part of a multi-component defoamer composition comprised of a hydrophobic solid and one or more reaction products according to the invention dispersed in an inert, water insoluble carrier fluid. The hydrophobic solid is any solid that is insoluble in the carrier fluid and having a particle size of less than about 70 microns. Examples of the hydrophobic solid include, but are not limited to, waxes such as polyethylene wax, ethylene-bis-stearamide; inorganic powders such as silica. Mixtures of various types of hydrophobic solids can also be used. The carrier fluid useful in the processes and compositions according to the invention is any water-insoluble liquid that such as paraffin oil, naphthenic oils, liquid hydrocarbons, tall oil fatty acids and alkoxylated tall oil fatty acids, fatty alcohols and alkoxylated fatty alcohols, liquid polypropylene oxide, liquid polyethylene oxide, liquid poly(ethylene oxidepropylene oxide), or any combination thereof. A defoaming effective amount of such a multi-component defoamer composition will be readily determinable by one of ordinary skill in the art and will typically vary from about 0.1% by weight to about 10%, preferably from about 0.1 to about 1.0% by weight.
This embodiment of the defoamer according to the invention can be made by mixing one or more reaction products according to the invention, a hydrophobic solid and a water-insoluble liquid carrier capable of dissolving or dispersing the hydrophobic solid and the reaction product at a temperature sufficient to melt the hydrophobic solid. Preferably, the above process can be modified by using a portion of the liquid carrier in the mixing step followed by the addition of the warm mixture to a second portion of liquid carrier at room temperature.
The reaction products according to the invention are the products of the reaction of epichlorohydrin and compounds having the formula II
R3(EO)n(PO)mOHxe2x80x83xe2x80x83(II)
wherein R3 is a substituted or unsubstituted, saturated or unsaturated aliphatic moiety having from 4 to 22 carbon atoms; a substituted alkyl or alkenyl group having from 4 to 22 carbon atoms wherein; n is a number from 0 to 50 and m is a number from 0 to 50; and epichlorohydrin wherein the mole ratio of epichlorohydrin to (II) is from about 0.60/1 to about 2/1 and preferably from about 0.80/1 to about 2/1. These products are described in copending application Ser. No. 08/783,224, filed on Jan. 14, 1997 (now U.S. Pat. No. 5,827,453).
In regard to the alkoxylates of formula 11, % can be any substituted or unsubstituted, saturated or unsaturated aliphatic moiety having from 4 to 22 carbon atoms. Thus R3 can be a linear or branched alkyl group, a linear or branched alkenyl or alkynyl group, a saturated carbocyclic moiety, an unsaturated carbocyclic moiety having one or more multiple bonds, a saturated heterocyclic moiety, an unsaturated heterocyclic moiety having one or more multiple bonds, a substituted linear or branched alkyl group, a substituted linear or branched alkenyl or alkynyl group, a substituted saturated carbocyclic moiety, a substituted unsaturated carbocyclic moiety having one or more multiple bonds, a substituted saturated heterocyclic moiety, a substituted unsaturated heterocyclic moiety having one or more multiple bonds. Examples of the above include but are not limited to an alkyl group having from 4 to 22 carbon atoms, an alkenyl group having from 4 to 22 carbon atoms, an alkynyl group having from 4 to 12 carbon atoms. R3 can also be an arenyl group. Arenyl groups are 10 alkyl-substituted aromatic radicals having a free valence at an alkyl carbon atom such as a benzylic group. The preferred value of R3 is an alkyl group having from 4 to 22 carbon atoms and most preferably an alkyl group having from 8 to 10 carbon atoms. The degree of ethoxylation is preferably from 2 to about 50 with the most preferred being from about 4 to about 50 while the degree of propoxylation can vary from 0 to 50. The degree of propoxylation will be determined by the desired degree of water solubility or miscibility. The water solubility or miscibility will ultimately be determined by such factors as the number of carbon atoms in R3, the relative amounts EO to PO and the effect of PO on the biodegradability of the final defoamer. The water solubility or miscibility of a defoamer according to the invention and the interrelationships between the number of carbon atoms in R3, the relative amounts EO and PO and the biodegradability of the final product will be readily determinable by one of ordinary skill in the art.
The method according to the invention can be used to control foam generated by any type of aqueous system having a surface tension below that of water such as aqueous-based personal care products as shampoos, facial cleaners, liquid hand soaps, and the like, and polymer latexes and latex paints. The defoaming compositions and methods are especially useful for controlling foam in polymer latexes and latex paints.